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texas star 400

The resistors are old, but I have seen this neg feedback before, they can be found more in older amps, like these pictured here.
There is a thread about this

http://www.worldwidedx.com/threads/sommerkamp-pa-100.81987/


73
Jeff
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close tolerance resistors.
 
It's a class C amp. Every TS amp I have every heard on the air is dirty and platters 3 channels up & down and on some harmonics as well.
Operators can and do go beyond operating amps beyond the specs and harmonics will follow. However, the Texas Star amps are AB biased; not C biased. So if these amps are run as specified, they should be clean. They exist legally as 10m amps; let's not forget that fact . . .
 
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First off, most TS amplifiers are biased AB. At least at idle. Now if the amp is splattering, a lot of times this is because mic gain is cranked and or someone has been inside radio and cut limiter/ spread the TVI filter circuit so much there is no filtering and did a wonderful diode mod to the modulation. Meaning the radio is a pile of junk. The amp amplifies the junk it is fed. It could also be the receiving radio has had the receive opened up. Meaning adjacent channel rejection is gone. Some have poor signal rejection to begin with. I say most TS, because all the 1pills modulator/ mod V are class C. Don't get me wrong, TS amps have issues. But they are far better than the average amp out there. Just drive amp what it is rated for. I see a lot of these peaked out 29's doing 50w pep. Yet they dk4w and swing only swing to 5w average. Same with a lot of these exports. 40-70 even 80w pep with these cheap fet's as finals that weren't even intended for RF. They were designed for switching power supplies or PWM circuits. So the amp may be the problem, but usually it's something else. Ok I'm done ranting.
 
I agree with what Crusher has posted, if you feed any amp a crappy signal, it is going to produce a crappy signal.

I have been running a Texas Star 500V on ten and twelve meters for about 10 years now with not one bad signal report, made hundreds of contacts with it.
Never had a complaint that I was creating splatter of any kind.
I have had several different radios in front of it, A President Lincoln, HR 2510, RCI 6900F25 and a RCI 2950DX radio.
It seems to have a sweet spot about 300/350 watts.
Please do not blame the equipment when it is operator error that is creating the problem.
The bias is not bulletproof by any means, yes it would be great of they would redesign it with adjustable electronic voltage regulated bias with temp compensation, and add a second relay just to control it.
BUT, for what they are, it is a step above the run of the mill CB style amps with no bias at all.
Try running a out of the box boomer clone amp on ten meters and see what kind of comments you get about signal quality.


73
Jeff
 

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